code: def parse_expr(s: str):
      from pyparsing import ParseException
  
      try:
          result = get_parser().parseString(s, parseAll=True)
      except ParseException as exc:
          format_and_raise_parse_error(exc)
          raise AssertionError("unreachable")  # noqa: B904
  
      joined = result.asList()
      assert len(joined) == 1
      return joined[0]
  
imports: import os
  import re
  import typing
  from collections.abc import Iterable, Mapping
  from functools import singledispatch
  from funcy import memoize, rpartial
  from dvc.exceptions import DvcException
  from dvc.utils.flatten import flatten
label_desc: Use image node_id 15 for calling a global function with example usage: parse_expr(s) and returns: joined